Field of the Invention
The present invention relates to a semi-finished product for the production of connection systems for electronic components and a method for producing connection systems for electronic components.
Description of the Related Art
In the context of the present invention, the term“connection system for electronic components” encompasses printed circuit boards, also referred to as printed wire boards, substrates and the like, which are altogether panels carrying and electrically connecting electronic components such as microchips, transistors, LEDs etc. and, hence, form vital parts of all kinds of electronic products like (tablet) computers, smartphones and the like. For the sake of simplicity, the following description is directed to printed circuit boards only, the person skilled in the art will, however, appreciate that every aspect of the invention and the following description is applicable also to substrates as just described and defined. Printed Circuit boards have a more or less complex structure depending on the specific application. In general a printed circuit board has a plurality of alternately applied conductive and insulating layers wherein the conductive layers are bonded together by hardening panels or plies of glass fibers impregnated with organic resin, said panels forming the insulating layers. Such panels for use in the production of printed circuit boards are widely known in the industry as “prepregs” (preimpregnated fibers), which are delivered and processed in an uncured, hence viscous state of the organic resin. The actual insulating layer results when the organic resin has cured. The insulating layers carry conductive layers, for example formed of copper foil, the conductive layers being appropriately processed to form wirings to electrically connect the electronic components. Modern printed circuit boards allow for a high degree of integration of electronic components and their appropriate wiring. In the technical field of printed wire boards, substrates are known to offer a similar functionality in terms of alternately applied conductive and insulating layers, however, substrates are much smaller and often serve to connect a microchip to a printed circuit board. To this end, the insulating layers of substrates are often produced of glass or ceramic materials which allows for smaller, high-precision structures.
There is, however, a constant need for further miniaturization in the electronic industry in order to provide consumers and professionals with ever smaller yet more capable electronic devices and installations which require more electronic components to be packaged and wired in a smaller space. Many electronic components, nowadays, are produced in nanometer-scale so that very often the printed circuit boards or substrates carrying and connecting the electronic components are the limiting parts in terms of miniaturization of electronic devices. The conductive layers and insulating layers making up a printed circuit board cannot easily be made thinner, since the bonding of the layers, which is often carried out by laminating layer after layer requires a certain mechanical stability in order to prevent undulating or even tearing of the bonded layers under the mechanical stresses that arise during lamination. Moreover, when the thickness of the layers falls below a certain limit, the handling of the very thin material previous to processing becomes increasingly critical due to buckling of the materials.
There have been attempts to combine groups of alternately applied conductive layers and insulating layers forming printed circuit boards on a carrier layer in order to have a combined thickness of the very thin boards to be produced so that the above described problems of buckling and tearing can be avoided or alleviated. There was, however, a problem with these attempts insofar as the groups of conductive layers and insulating layers, hence, the future printed circuit boards tended to skid and swim on the carrier layer during lamination. Moreover, it was detrimental that during production chemicals could leak into the area of the carrier layer, which was undesirable as those chemicals promoted undesirable etching of conductive layers in the region of the separation area. Furthermore, the chemicals in the separation area were carried into different chemical stages in the production line, so that those chemicals were prematurely contaminated and eventually spent.